1. Field of the Invention
This invention is related to an apparatus and method for producing a denture that is a duplicate of an original denture, and can be provided to a denture wearer when the original denture is lost. The invention also relates to the fabrication of a mold that conforms to the shape of the original denture.
2. Description of the Prior Art
Several patents discuss situations in which copies of dentures may be desirable and disclose methods of making those denture copies. It has been suggested that a temporary denture can be fabricated in a dentist's office so that the denture wearer will have a temporary denture to use while the dentist makes repairs to the original denture. It has also been suggested that a replacement denture can be fabricated using a indexed impression of a worn denture. It has also been suggested that denture wearers may require at least one identical denture in case of loss, breakage or repair of the original denture.
U.S. Pat. No. 4,521,193 discloses one method of making a temporary denture in which an impression is first made of the outer surfaces of the denture wearer's permanent denture. A molding material, such as an irreversible hydrocoloid, for example alginate, is mixed with water to form a colloidal suspension and placed in a molding shell. The permanent denture is then placed in the molding material to form an impression of the exterior surfaces of the permanent denture. The permanent denture is then removed and the molding material is allowed to set. A polymerizable liquid acrylic material with tooth colored powder is then placed in the tooth area of the impression. Methylmethacrylate is a suitable dental acrylic that can be used to form a portion of this temporary denture. The remaining surface of the impression is then covered with a pink colored acrylic to form a layer, slightly thinner than the permanent denture. The acrylic is then cured forming an acrylic shell. A soft denture liner is then placed on the inside portion of this acrylic shell. The shell and inner liner are then placed in the denture wearer's mouth. After the liner has set, the temporary denture is removed and trimmed. This method requires the assistance of the denture wearer, which may not be possible if the patient is elderly or suffers from dementia. This method is also primarily intended to provide a temporary denture that is suitable for short term use, while a permanent denture is repaired or replaced.
U.S. Pat. No. 5,711,668 discloses a method in which an impression mold of a worn denture is made by embedding the worn denture in an impressionable material, such as alginate, in a two part dental flask. The worn denture is removed and the impression mold is filled with methyl methylmethhacrylate, or a similar material, to form a stint that replicates the original denture. Adjustments or modifications can then be made to the stint. For example, the proper bite opening can be restored or the dentures can be modified to properly center the upper and lower jaw, by using bite material impressions. A two layered model is then obtained by filling undercuts in the stint with a resilient material, and clipping these resilient layers to a rigid layer formed by dental stone or gypsum poured onto the resilient layer. The resilient layer permits removal of the stint from the two layered model. The stint and the two layered model are mounted in an articulator and modifications are made to insure proper vertical positioning and centering. The stint is removed and the two layered model is used to construct a baseplate corresponding to soft tissue surfaces and teeth are set according to information gathered in a wax wafer, and wax try-in is conducted. Dental stone is then poured into the baseplate, after which a new denture is finished using standard processing techniques. Although this technique allows useful information to be gathered from an older worn denture, it does not provide a means for duplicating a denture or quickly replacing a lost denture. The production of a new denture by this method would appear to require considerable time and effort on the part of the dentist or a dental technician. This method instead is directed to the use of a mold and stint derived from an original denture to obtain information useful for the fabrication of a new denture that may or may not be identical to the original denture.
U.S. Pat. No. 5,607,628 discloses a method of making a copy of a denture in which the gum portion of a denture is embedded up to the lower level of the teeth in a dental molding material, such as hard plaster, to form a mold. Before the hard plaster completely hardens, excess plaster is removed to free the denture. The mold is then placed in a lower portion of a flask and is fixed by surrounding it with a plaster of medium hardness. A polymerizable resin material, such as a silicone resin, is then poured over the tooth portion of the denture to form a mold for the tooth portion. The upper part of the flask is filled with medium hard plaster and the flask is placed in a dental type press. After the plaster hardens, the mold surrounding the teeth is removed and a polymethylmethacrylate is deposited in this half of the mold to form the teeth. The teeth are then removed, individually separated and individually trimmed. The individual teeth are then repositioned in the mold. A resin suitable for forming the gum base is then deposited in the other mold and in the remaining space in the tooth mold in an operation know as wedging, and the two halves of the flask are closed an locked in a hydraulic press. This prior art method does not however appear to use a dimensionally stable material only to make a mold or impression of only the tissue side of a denture while using a resilient or more deformable material to make a mold or impression of the remainder of the denture.
The loss of dentures by the elderly, especially by those who suffer from some degree of dementia, is a problem for several reasons. In many cases the elderly denture wearer cannot provide the assistance to and interaction with a dentist who is attempting to make a replacement denture. Properly fitting dentures are thus difficult and/or expensive to fabricate. Indeed dental care for the elderly is a difficult task for the dentist and dental professional. For that reason, the dental care needs of the elderly may not be adequately served. Poor dental health, especially for the elderly, can lead to other problems, such as poor nutrition. The loss of dentures by the elderly is a particular problem in long term health care facilities. When an elderly denture wearer loses his or her dentures, it becomes difficult for them to eat properly, and in long term health care facilities in often becomes necessary to provide specially processed foods for that person. Of course, this increases the cost of health care and can be frustrating to that person's relatives. This problem leads to additional friction between those caring for the elderly resident of rest and nursing homes.
If a simple means of promptly replacing a lost denture were available, the problems of adequately caring for the elderly would be somewhat alleviated. A duplicate denture, that would be less expensive than a new denture, would be at least a partial solution to this problem. However, the new denture would have to fit properly, without extensive custom fitting, and it would often be necessary to fabricate the duplicate denture many years after construction of the original denture. Thus a mold of the original denture, fabricated at the time that the original denture was constructed, would need to be suitable for use many years later. The instant invention provides a mold and a method that could be used to fabricate a duplicate, properly fitting, denture, many years after construction of the original denture. This new mold uses a rigid, dimensionally stable material to form an impression of critical areas of the denture, and a more flexible material to form an impression of other areas of the denture where small variations would be less likely to cause discomfort when the duplicate denture is in use. The flexible material also facilitates removal of both the original and the duplicate denture from the mold without damage.